How do you determine the speed of an SSD ?

[chomper]

I know that SSD is supposed to be faster than a regular old Sata HD even a 7200RPM. but since there is no rotation speed on the SSD how do you judge the speed on them ? For example how would you compare the speed of a SSD to a 15000 RPM Sata ?

[thomasw333]

Read and Write speed, in mbps.
7,200 RPM Drive, READ 90MBS, WRITE 85MBS

SSD SATA III READ 550MBS, WRITE 500MBS.

[Kuu]

There's more to SSD's than just raw read and write speeds; you have access times which are virtually nonexistant compared to a normal HDD where it could take .1 second to get to a file and read it [or more]; that's the main reason why SSD's appear to be faster to most people.

[chomper]

Also I noticed that alot of ultrabooks have a 500GB HD and a 32GB SSD. IS there 2 individual HDs in there ?

[Kuu]

It technically counts as two drives, but the hardware makes them work together as one, the 32GB SSD works like RAM for the HDD, where it stores frequently used and accessed files based on certain usage patterns, with exceptions as to what does and doesn't get stored in it.

[tilleroftheearth]

I know that SSD is supposed to be faster than a regular old Sata HD even a 7200RPM. but since there is no rotation speed on the SSD how do you judge the speed on them ? For example how would you compare the speed of a SSD to a 15000 RPM Sata ?

Indeed 'supposed to be faster' is the key words...

You don't judge the speed on spec's or benchmarks or marketing or some fan on a forum that was used to fully un-optimized 5400 RPM HDD's and gets all excited with a 64GB mediocre example of what an SSD should be with no basis to back up his/her 'wow, this is fast' remarks.

What an SSD should be (basics):
All channels filled and each channel optimally interleaved and all managed with an intelligent controller to get the most real world work done with the least amount of power consumption with stability and reliability at the top of the list. Or, get an Intel SSD with at least 240GB capacity or more ).


How do you judge the speed? Simple - take your current working setup, duplicate it except for swapping in the SSD in question for the HDD (including all software, drivers and data needed to make your programs work) and then use it exactly (or as close to it as possible) as you did your HDD based setup. This is how you will see what is faster (and by how much - and if the $$$ to get that speed are worth it (to you) for the performance/productivity gained).

Even compared to a 15K RPM SATA or SAS drive, any (good) SSD will impress with faster boot times, faster program launches, faster shutdowns and faster copies OFF the drive (to another drive - SSD or HDD...). It will also continue to impress with any program that uses/runs off a database (LR4, for example) and/or reading/creating/modifying small files (such as PDF's).

Depending on the SSD in question, it may even impress in write speeds (but HDD's (ie. 1TB vRaptor) have now hit 200MB/s - dangerously close to SSD territory - close enough that it may not even matter (too much) if the SSD can do another few 10's of MB's/sec more (sustained, incompressible files...).

Another 'myth' you may want to prove/dispel during your testing is how much more power efficient (and heat producing...) the SSD in question is vs. the HDD it may be replacing when it is operating at it's extremes. Especially in a poorly designed notebook with bad/no/little ventilation for the storage subsystem - there are SSD's that take MORE power than the mechanical HDD it replaces.

Also consider that to keep an SSD operating at it's peak performance on a sustained/continuous basis you need to keep a lot of free space on it - ideally by partitioning it (at time of purchase - before any other usage) at up to 50% or less of it's nominal capacity. While this is only needed if you intend to punish the SSD (like, for a PS Scratch Disk...) for 8+hours every work day and need it to perform to at least close to it's spec's - depending on the actual workload the SSD is subject too can make this over-provisioning a matter of life and death (matter of weeks/months) to the SSD.

Finally, if you need to RAID (0/1/5/10/etc.) an SSD (for example: your data set won't fit on a single drive) - note that the SSD's in these arrays can degrade in a matter of days with the worst part being that you have to break the RAID - Secure Erase each drive and join them again in the RAID array you need/require (hope you make daily image backups...).

Having a solid baseline (of productivity) with your current system setup and setting up an identical SSD test system and seeing how that baseline moves (it won't be all positive, ime...) is the key to knowing (or how I would compare) to a 15K HDD.

If you don't want to do all that - there's always the truthful marketing to help you out...

[nipsen]

@chomper: Generally speaking, the flash storage.. because there's no mechanical parts.. has near instant access times, and time to max transfer. But there are extra logical operations involved when writing. It's really a large eprom. And as transistor size and cost has gone down -- that's really all there is to it.

And what it means is that short and large sectors will have the same instant peak transfer speed, etc. That's useful. Depending on the way the disk is set up, though, the throughput can be different. And you still get ssds with relatively low write speeds. This has to do with architecture and the internal controller on the disk, before the motherboard's IO controller interface(the sata port).

The write operations as well used to be a real pain, because for example Windows doesn't actually write to a disk before rewriting on top of other sectors again. Meaning that if you delete a file, then the sector is just marked as writeable, without the sector actually being wiped. So the next write operation would overwrite, etc. On an ssd, that would get sent to the controller, and you would get very erratic write performance, depending on whether the drive was prepared or not (because of that extra logical overhead having to do with how flash-storage works). But that's not really a problem at this point.

But it's a good question. How you rate the most expensive ssd towards a cheap one. Or if improvements were made lately that would make one purchase better than another.

Honestly, I think there's not much to say about that, because even the worst ssd, at the worst times - even one without automatic maintenance - still works faster than a hdd.. So for a normal consumer, it's not really a question about performance, but storage size and practical convenience.. A mechanical drive in an EeePC, for example -- counter-intuitive. So a very good option to put an ssd in those, even with the first terribly slow and terribly small ssds.

But then again - you could imagine striping two 500mb/s drives, and.. ideally.. max out the controller speed. Practically, though, you would want to get an ssd with a self-maintaining controller, so you can disable TRIM from the OS. And have one with high write speeds (sata 3/ towards 500mb/s). That's really the only interesting specs for us as users - that the disk can maintain a high transfer speed. And secondary, that it can deliver write speeds that are up towards the best hdds. ..and most disks on the market now can do that now.

If you're interested in how this has developed, though, you should take a look at the earliest EeePC reviews. That's where ssds made sense at the beginning.
jkkmobile: Asus Eee PC SSD read and write tests. 901 vs 900 vs 900 16G

Especially in a poorly designed notebook with bad/no/little ventilation for the storage subsystem - there are SSD's that take MORE power than the mechanical HDD it replaces.

:/ *cough* ..example?

Also consider that to keep an SSD operating at it's peak performance on a sustained/continuous basis you need to keep a lot of free space on it - ideally by partitioning it (at time of purchase - before any other usage) at up to 50% or less of it's nominal capacity. While this is only needed if you intend to punish the SSD (like, for a PS Scratch Disk...) for 8+hours every work day and need it to perform to at least close to it's spec's - depending on the actual workload the SSD is subject too can make this over-provisioning a matter of life and death (matter of weeks/months) to the SSD.

That's.. not really a problem with any average self-maintaining controller config nowadays, though..

Finally, if you need to RAID (0/1/5/10/etc.) an SSD (for example: your data set won't fit on a single drive) - note that the SSD's in these arrays can degrade in a matter of days with the worst part being that you have to break the RAID - Secure Erase each drive and join them again in the RAID array you need/require (hope you make daily image backups...).

..sounds like you had a great experience with setting up one of the first intel ssds for a server. Would love to hear the whole story

[tilleroftheearth]

nipsen,

examples of SSD's with higher power consumption than HDD's (during sustained use...) is the Samsung 830 series and the OCZ Vertex 4 series drives. Intel 510 Series drives are also very power hungry - but not as much as these two.

The only SSD that showed a real world reduction in power use (by demonstratably longer battery life...) in my systems and usage workflows is the Intel 320 Series 160GB models.

With regards to the 'its not a problem for average controllers...' comment - I can see that you're not pushing SSD's like I do - or at least you are not noticing the performance degrade even while Windows, programs and data is installed to any current SSD - let alone use them at the edge of their performance envelopes.

I'll concede that SSD's offer benefits that HDD's simply cannot match (mostly; no moving parts and now; small/tiny mSATA form factor(s)) - but that does not mean they are better, performance-wise (overall) than HDD's - especially at the smaller capacities.

You also have a very optimistic viewpoint of how far SSD's have advanced. The issues you think are no longer a problem are still here and very real for workflows that stress the storage subsystems substantially and continuously on a daily basis. For casual users; sure SSD's make today's systems feel like something from the future - especially compared to slow, unoptimized HDD's that are shipped by default by all manufacturers.

But for users that are used to the fastest HDD's in optimal setups (via partitioning and maintenance), some SSD's are just now starting to give a tangible performance/productivity difference with the right kind of tlc (again; partitioning and maintenance) in a workstation type real world workflow.

(Please note that 'productivity' is not startup, shutdown or program launches (that is simply 'snappiness' of the O/S, not productivity) - here, it is used simply to indicate in minutes/hours per day/week/month/year how much more work an SSD achieves over an HDD in the same setup once inside the productivity program/suite of choice).

[davidricardo86]

Since most of us here are average users or consumers, we use consumer line of ssds (basically the "cheap" stuff) & it works great! Some better than others but for the most our needs are satisfied. If you're so concerned about these (imo little) issues with consumer ssds so much & how they don't keep up with your "workloads & workflows", then why don't you step up to more expensive heavy-duty enterprise/business ssds? Apparently your usage patterns are so much more "extreme" than anyone elses here that it would warrant the best ssd money could buy (if money were no object) yet you're not using one (that we know of).

What exactly are you doing & using your ssd(s) for? Can you elaborate on your high performance usage & how you're pushing them to the "edge" on a daily basis? What exactly is a "workstation type real world workflow & how are you substantially & continously pushing your consumer ssd within a productivity program or suite?"

Again, id like to know where to get the software to test power consumption of my consumer ssds to see if its operating in accordance to what these reviewers are saying. Id like to verify, not just from myself but from as many users, what the actual statistics & data are. For me, one review/one website is not enough data, & its not the end all. I believe there will be (slight) variations even between two of the same ssd. Just like how not all cpus operate exactly the same, even if they are the exact same models.

Sent from my SPH-M580 using Tapatalk

[nipsen]

Ouch, those stats didn't seem very good.. I have a force gt drive, it maxes out at 2.5W or so (idles at 0.5-0.3). I didn't think many drives went higher than that.

Difficulty getting sustained throughput, and that this is variable, is a good point, though. And I know some drives just crash really badly on the performance when the disk starts to become full, and you get the rewrites more consistently. Even if the Intel disk I tested.. a year ago.. still didn't go below 80mb/s or so. Which is pretty fast for worst case scenarios.. When that also doesn't actually affect the read speed, or access times, I wasn't exactly complaining.

Besides, once you reach the queue-depth on an hdd, or create workloads that have small and spread out reads and writes, you get a similar effect (with lower transfer speeds on average - and you can get those extremely fast, if you create the right loads..). You get that even on the most ridiculously expensive drive. You certainly get it quickly on a normally priced drive. And placing data on particular spots on the drive, to make sure you don't get written things back and forth from different programs, or splitting on partitions, setting up a stripe, that kind of thing - this isn't done in a hurry, or very easily. While self-maintenance on an ssd, or letting it run trim once in a while. That arguably gives you better performance than the extremely carefully kept hdd stripe, etc.... this is literally no effort at all.

So since I'm not dependent on write speeds being consistent, and don't need massive storage space -- I notice an improvement with the things I do. Compiling java-projects, running things with some access to the disk while other tasks are running, and so on. Then the difference is huge. Because those things have always maxed the drive-queue on a normal disk before, even if it had reasonably large cache and so on. So now the actual operation is faster - and anything else I'm doing that needs light read/write on the disk is still snappy.

Definitely agree that it's not magic, though. That there are problems with this, and that they've been serious. Some of the OCZ drives were notoriously bad, and the firmware is still patched on their drives. Not disputing that. Still - I'm not going to start saying that "well, you could just buy this drive for €100, plug it in -- or, you can buy these two disks and stripe them, use five times the power, get more noise, spend some time setting it up -- and get about the same performance. So therefore it's just a matter of preference!". Can't do that.

Can't bring myself to pull some Anandtech quote either, and go: "The throughput degradation goes from 500mb/s to barely 180mb/s! Which is merely 36% of the advertised speed! A far cry from the much smaller 180mb/s to 150mb/s reduction that the more solid good old hdds do! Oh, yes, this is a load of false advertisement, and SSDs are fraud! Very questionable, and not reliable at all! Here's a list of hdds that have better best case scenarios than this ssd's absolute worst case! Make your informed choice!". You know.. There's a tendency that people write things like that. Or actually invent new stress-tests for ssds that would croak an hdd instantly.

.. But it is a good question - how do you see the difference between the best and the worst ssds. And I think sustained througput is the important part - to avoid the situations you've seen when the write performance drops extremely far down for no reason. Or that conditions for normal full-speed reads are kept when the disk starts to fill up. ..do manufacturers even have something suggesting that in their specs, by the way..? I went by Sandra tests when I bought a drive..